1. Field of the Invention
The present invention relates to an image forming unit system having a sheet handling unit connected to a post-stage of an image forming unit represented by a printer, a copying machine, or the like.
2. Description of the Related Art
An image forming unit system has been put into practical use. In such an image unit system, a sheet handling unit represented by a stacker provided with a sheet tray, a finisher provided with an post-processing unit such as a stapler, or the like, is connected to a post-stage of an image forming unit represented by a printer, a copying machine, etc. so that the sheet handling property, working efficiency, etc. after printing are improved. In the background art, such an image forming unit system had a configuration in which when the system was operated, the image forming unit and the sheet handling unit were connected to each other through an interface signal line, or the like, so as to be able to communicate each other so that the sheet carrying-in rate of the sheet handling unit was controlled in accordance with the sheet ejection rate of the image forming unit while the two units were communicating each other.
Accordingly, in the case of such a technique in the background art, there was a defect that not only the controlling of the sheet handling unit was complex but also the cost of the system was high.